Effect of different formulations of heparin analogues on radiotherapy skin markers: A cross-sectional study

This observational study evaluated the effects of different topical heparinoid formulations on the visibility of Inkbox skin markers used in radiotherapy (RT). Skin markers are essential for accurate patient positioning and precise radiation delivery during RT. Conventional skin markers often suffer from diminished visibility due to sweating, friction, or the use of topical agents. Inkbox®, a plant-based, long-lasting alternative that penetrates the stratum corneum, provides durable and reliable skin markings. Heparinoid preparations, commonly prescribed to prevent radiation-induced dermatitis, may influence marker visibility; however, their compatibility with Inkbox has not been systematically studied. In this observational study, 7 healthy male volunteers aged 22 to 30 years participated. Following the application of Inkbox markers, 4 different heparinoid formulations – foam, cream, soft ointment, and lotion – were applied to the skin. A control group with no heparinoid application was also included. Marker visibility was quantitatively assessed every other day over a two-week period using spectrophotometry, measuring lightness (L*). Statistical comparisons between groups were performed using t -tests. Spectrophotometric analysis revealed no statistically significant differences in L* values among any of the heparinoid formulations and the control group ( P  > .05), indicating that none of the tested formulations adversely affected marker visibility or intensity. This study demonstrates, through objective spectrophotometric evaluation, that Inkbox skin markers maintain their visibility regardless of concurrent topical heparinoid use. These findings support the clinical utility of Inkbox as a robust skin marking method during RT, including in patients undergoing dermatological treatments. Further research involving larger and more diverse patient populations is warranted to confirm these results.